Radio transmission device and radio transmission method

ABSTRACT

It is possible to improve the CQI reception performance even when a delay is caused in a propagation path, a transmission timing error is caused, or a residual interference is generated between cyclic shift amounts of different ZC sequences. For the second symbol and the sixth symbol of the ACK/NACK signal which are multiplexed by RS of CQI, (+, +) or (−, −) is applied to a partial sequence of the Walsh sequence. For RS of CQI transmitted from a mobile station, + is added as an RS phase of the second symbol and − is added as an RS phase of the sixth symbol. A base station (100) receives multiplexed signals of ACK/NACK signals and CQI signals transmitted from a plurality of mobile stations. An RS synthesis unit (119) performs synthesis by aligning the RS phase of CQI.

BACKGROUND Technical Field

The present invention relates to a radio transmitting apparatus andradio transmitting method.

Description of the Related Art

Mobile communication applies ARQ (Automatic Repeat reQuest) to downlinkdata from a wireless communication base station apparatus (hereinafterabbreviated as “base station”) to a wireless communication mobilestation apparatus (hereinafter abbreviated as “mobile station”). Thatis, the mobile station feeds back an ACK/NACK signal showing an errordetection result of downlink data to the base station. The mobilestation performs a CRC check of downlink data, and, if CRC=OK (i.e., noerror), feeds back an ACK (Acknowledgement) to the base station, or, ifCRC=NG (i.e., error present), feeds back a NACK (NegativeAcknowledgement) to the base station. This ACK/NACK signal istransmitted to the base station using an uplink control channel such asa PUCCH (Physical Uplink Control Channel).

Further, the base station transmits control information for indicating adownlink data resource allocation result, to the mobile station. Thiscontrol information is transmitted to the mobile station using adownlink control channel such as L1/L2CCHs (L1/L2 Control Channels).Each L1/L2CCH occupies one or a plurality of CCEs (Control ChannelElements). In case where one L1/L2CCH occupies a plurality of CCEs, oneL1/L2CCH occupies a plurality of consecutive CCEs. According to thenumber of CCEs required to report control information, the base stationallocates one of a plurality of L1/L2CCHs, to each mobile station, andmaps control information on the physical resources associated with theCCEs occupied by each L1/L2CCH and transmits control information.

Further, to associate CCEs and PUCCHs for efficient use of downlinkcommunication resources is being studied. According to this association,each mobile station can decide the PUCCH number to use to transmit anACK/NACK signal from each mobile station, based on the CCE numberassociated with the physical resources in which that control informationfor that mobile station is mapped.

Further, as shown in FIG. 1, to code-multiplex a plurality of ACK/NACKsignals from a plurality of mobile stations by spreading using ZC(Zadoff-Chu) sequences and Walsh sequences (see Non-Patent Document 1)is being studied. Note that the sequence length of a pure ZC sequence isa prime number, and therefore a pseudo ZC sequence of a sequence lengthof 12 is generated by cyclically extending part of the ZC sequence of asequence length of 11. Also, note that a pseudo ZC sequence will also bereferred to as a “ZC sequence” below for ease of explanation. In FIG. 1,(W₀, W₁, W₂ and W₃) represents a Walsh sequence of a sequence length of4. As shown in FIG. 1, a mobile station first performs first spreadingof an ACK or NACK in an SC-FDMA symbol using a ZC sequence (having asequence length of 12) in the frequency domain.

Next, the ACK/NACK signal after the first spreading is subjected to anIFFT (Inverse Fast Fourier Transform) according to W₀ to W₃. TheACK/NACK signal spread using a ZC sequence of a sequence length of 12 inthe frequency domain is transformed into a ZC sequence of a sequencelength of 12 in the time domain by this IFFT. Then, the signal after theIFFT is further subjected to second spreading using the Walsh sequence(having a sequence length of 4). That is, one ACK/NACK signal is mappedover four SC-FDMA symbols. Similarly, other mobile stations spreadACK/NACK signals using ZC sequences and Walsh sequences.

Note that different mobile stations use ZC sequences of different cyclicshift amounts in the time domain or different Walsh sequences. Here, thesequence length of the ZC sequence in the time domain is 12, so that itis possible to use twelve ZC sequences with cyclic shift amounts of 0 to11 generated from the same ZC sequence. Further, the sequence length ofa Walsh sequence is 4, so that it is possible to use four differentWalsh sequences. Consequently, it is possible to code-multiplex ACK/NACKsignals from maximum 48 (12×4) mobile stations in the idealcommunication environment.

ACK/NACK signals from other mobile stations are spread using ZCsequences of different cyclic shift amounts or different Walshsequences, so that the base station can separate ACK/NACK signals frommobile stations by performing despreading using a Walsh sequence andcorrelation processing of ZC sequences. Further, as shown in FIG. 1,block spreading codes of a sequence length of 3 is used for RSs(Reference Signals). That is, RSs from different mobile stations arecode-multiplexed using second spreading sequences of a sequence lengthof 3. By this means, RS components are transmitted over three SC-FDMAsymbols.

Here, the cross-correlation between ZC sequences of different cyclicshift amounts generated from the same ZC sequence is virtually 0.Consequently, in the ideal communication environment, as shown in FIG.2, a plurality of ACK/NACK signals code-multiplexed using ZC sequencesof different cyclic shift amounts (cyclic shift amounts of 0 to 11) canbe separated in the time domain by correlation processing in the basestation without inter-code interference.

However, due to various influences such as transmission timing lags inmobile stations, multipath delay waves and frequency offset, a pluralityof ACK/NACK signals from a plurality of mobile stations do not alwaysarrive at the base station at the same time. For example, as shown inFIG. 3, in case where the transmission timing for an ACK/NACK signalspread using a ZC sequence of a cyclic shift amount of 0 is delayed fromthe right transmission timing, the correlation peak of the ZC sequenceof a cyclic shift amount of 0 appears in the detection window for the ZCsequence of a cyclic shift amount of 1. Further, as shown in FIG. 4, incase where an ACK/NACK signal spread using a ZC sequence of a cyclicshift amount of 0 produces a delay wave, interference due to this delaywave leaks and appears in the detection window for the ZC sequence of acyclic shift amount of 1. That is, in these cases, the ZC sequence of acyclic shift amount of 0 interferes with the ZC sequence of a cyclicshift amount of 1. Therefore, in these cases, performance of separatingan ACK/NACK signal spread using a ZC sequence of a cyclic shift amountof 0 and an ACK/NACK signal spread using a ZC sequence of a cyclic shiftamount of 1 deteriorates. That is, if ZC sequences of consecutive cyclicshift amounts are used, there is a possibility that the performance ofseparating ACK/NACK signals deteriorates. To be more specific, althoughthere is a possibility that interference due to transmission timing lagsoccurs together with interference from a cyclic shift amount of 1 to acyclic shift amount of 0 and interference from a cyclic shift amount of0 to a cyclic shift amount of 1, as shown in the figure, the influenceof a delay wave only produces interference from a cyclic shift amount of0 to a cyclic shift amount of 1.

Therefore, conventionally, in case where a plurality of ACK/NACK signalsare code-multiplexed by spreading using ZC sequences, enough cyclicshift amount differences (i.e., cyclic shift intervals) are providedbetween ZC sequences to prevent inter-code interference from occurringbetween ZC sequences. For example, assuming that the difference in thecyclic shift amount between ZC sequences is 2, ZC sequences of sixcyclic shift amounts of 0, 2, 4, 6, 8 and 10 in twelve cyclic shiftamounts of 0 to 11 are used for first spreading of ACK/NACK signals.Consequently, in case where ACK/NACK signals are subjected to secondspreading using Walsh sequences of a sequence length of 4, it ispossible to code-multiplex ACK/NACK signals from maximum 24 (6×4) mobilestations. However, there are only three patterns of RS phases, andtherefore only ACK/NACK signals from 18 mobile stations can actually bemultiplexed.

Non-Patent Document 1: “Multiplexing capability of CQIs and ACK/NACKsform different UEs,” 3GPP TSG RAN WG1 Meeting #49, R1-072315, Kobe,Japan, May 7-11, 2007

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

By the way, in a PUCCH of 3GPP LTE, not only the above-describedACK/NACK signals but also CQI (Channel Quality Indicator) signals aremultiplexed. While an ACK/NACK signal is one symbol of information asshown in FIG. 1, a CQI signal is five symbols of information. As shownin FIG. 5, a mobile station spreads a CQI signal using a ZC sequence ofa sequence length of 12 and a cyclic shift amount of P, and performs anIFFT of the spread CQI signal and transmits the CQI signal. In this way,Walsh sequences are not applicable to CQI signals and therefore theWalsh sequences cannot be used to separate an ACK/NACK signal and CQIsignal. In this case, by using ZC sequences to despread an ACK/NACKsignal and CQI signal spread using ZC sequences associated withdifferent cyclic shifts, the base station can separate the ACK/NACKsignal and the CQI signal with little inter-code interference.

However, although, in the ideal communication environment, a basestation can separate an ACK/NACK signal and CQI signal using ZCsequences, cases might occur depending on, for example, the condition ofdelay on channels as described above where the orthogonality of cyclicshift sequences breaks and a CQI signal is interfered from an ACK/NACKsignal. Further, when despreading is performed using ZC sequences toseparate a CQI signal from an ACK/NACK signal, a little inter-codeinterference from the ACK/NACK signal remains. As shown from FIG. 1 andFIG. 5, an ACK/NACK signal and CQI signal employ different signalformats and their RSs are defined in different positions (that is, thepositions of these RS are optimized independently in case where only anACK/NACK signal is received and in case where only a CQI signal isreceived). Therefore, there is a problem that the amount of interferencefrom an ACK/NACK signal to RSs of a CQI signal varies depending on thecontent of data of the ACK/NACK signal or the phases of W₁ and W₂ usedfor the ACK/NACK signal. That is to say, even though RSs are importantportions for receiving a CQI signal, there is a possibility that theamount of interference in these RSs cannot be predicted, therebydeteriorating CQI receiving performance.

According to an aspect of the present invention, a radio transmittingapparatus and radio transmitting method are provided for improving CQIreceiving performance, for example, when a delay occurs on a channel,when transmission timing lags occur or when residual interference occursbetween different cyclic shift amounts of ZC sequences.

Means for Solving the Problem

The radio transmitting apparatus according to the present inventionemploys a configuration which includes: an acknowledgement/negativeacknowledgement signal transmission processing section that spreads anacknowledgement/negative acknowledgement signal using an orthogonalsequence; a reference signal phase adding section that adds a phaseaccording to part of the orthogonal sequence, to a reference signal of achannel quality indicator multiplexed with the acknowledgement/negativeacknowledgement spread using the orthogonal sequence; and a transmittingsection that transmits a channel quality indicator signal including thereference signal to which the phase is added.

The radio transmitting method according to the present inventionincludes: an acknowledgement/negative acknowledgement signaltransmission processing step of spreading an acknowledgement/negativeacknowledgement signal using an orthogonal sequence; a reference signalphase adding step of adding a phase according to part of the orthogonalsequence, to a reference signal of a channel quality indicatormultiplexed with the acknowledgement/negative acknowledgement signalspread using the orthogonal sequence; and a transmitting step oftransmitting a channel quality indicator signal including the referencesignal to which the phase is added.

Advantageous Effects of Invention

According to the present invention, it is possible to improve CQIreceiving performance when a delay, for example, occurs on a channel,when transmission timing lags occur or when residual interference occursbetween different cyclic shift amounts of ZC sequences.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a method of spreading an ACK/NACK signal;

FIG. 2 shows correlation processing of an ACK/NACK signal spread using aZC sequence (in case of the ideal communication environment);

FIG. 3 shows correlation processing of an ACK/NACK signal spread using aZC sequence (in case where there are transmission timing lags);

FIG. 4 shows correlation processing of an ACK/NACK signal spread using aZC sequence (in case where there are delay waves);

FIG. 5 shows a method of spreading a CQI signal;

FIG. 6 is a block diagram showing a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 7 is a block diagram showing a configuration of a mobile stationaccording to Embodiment 1 of the present invention;

FIG. 8 shows how an ACK/NACK signal is transmitted and a CQI signal isgenerated;

FIG. 9 shows how a Walsh sequence that is frequently used and RS phasesof CQI are made orthogonal;

FIG. 10 shows how RS phases of CQI are adaptively controlled accordingto a Walsh sequence that is frequently used;

FIG. 11 shows how an ACK/NACK signal is transmitted and a CQI signal isgenerated in case where the positions of RSs of CQI are multiplexed withRSs of an ACK/NACK;

FIG. 12 shows how an ACK/NACK signal and a CQI signal are multiplexedaccording to Embodiment 2 of the present invention;

FIG. 13 shows how an ACK/NACK signal and a CQI signal are multiplexed inanother way according to Embodiment 2 of the present invention;

FIG. 14 is a block diagram showing a configuration of a base stationaccording to Embodiment 3 of the present invention;

FIG. 15 is a block diagram showing a configuration of a mobile stationaccording to Embodiment 3 of the present invention;

FIG. 16 shows how an ACK/NACK signal and a CQI signal that aretransmitted at the same time are generated; and

FIG. 17 shows how an ACK/NACK signal and a CQI+ response signal aremultiplexed according to Embodiment 4 of the present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be explained indetail with reference to the accompanying drawings.

Embodiment 1

FIG. 6 shows a configuration of base station 100 according to Embodiment1 of the present invention, and FIG. 7 shows a configuration of mobilestation 200 according to Embodiment 1 of the present invention.

Further, to avoid complicated explanation, FIG. 6 shows components thatare related to transmission of downlink data and reception of anACK/NACK signal in response to this downlink data in uplink that areclosely related to the present invention, and the components related toreception of uplink data will not be shown or explained. Similarly, FIG.7 shows components that are related to reception of downlink data andtransmission of an ACK/NACK signal in response to this downlink data inuplink that are closely related to the present invention, and componentsrelated to transmission of uplink data will not be shown or explained.

Further, a case will be explained below where a ZC sequence is used forfirst spreading and a Walsh sequence is used for second spreading.However, instead of ZC sequences, sequences that can be separated basedon different cyclic shift amounts may be used for first spreading.Similarly, orthogonal sequences other than Walsh sequences may be usedfor second spreading.

Further, a case will be explained below where a ZC sequence of asequence length of 12 and a Walsh sequence (W₀, W₁, W₂ and W₃) of asequence length of 4 are used. However, the present invention is notlimited to these sequence lengths.

Further, in the following description, twelve ZC sequences of cyclicshift amounts of 0 to 11 are represented as ZC #0 to ZC #11, and fourWalsh sequences of sequence numbers 0 to 3 are represented as W #0 to W#3.

Furthermore, in the following description, assume that L1/L2CCH #1occupies CCE#1, L1/L2CCH #2 occupies CCE#2, L1/L2CCH #3 occupies CCE#3,L1/L2CCH #4 occupies CCE#4 and CCE#5, L1/L2CCH #5 occupies CCE#6 andCCE#7, and L1/L2CCH #6 occupies CCE#8 to CCE#11.

Still further, in the following explanation, assume that a CCE numberand a PUCCH number defined by the cyclic shift amount of a ZC sequenceand a Walsh sequence number are associated one by one. That is, CCE#1corresponds to PUCCH #1, CCE#2 corresponds to PUCCH #2, CCE#3corresponds to PUCCH #3 and . . . .

In base station 100 shown in FIG. 6, a downlink data resource allocationresult is inputted to uplink RS phase determining section 101, controlinformation generating section 102 and mapping section 108.

Uplink RS phase determining section 101 determines which one of “+” and“−” is used for the RS phases (i.e., the phase of the second symbol andthe phase of the sixth symbol) of CQI transmitted from a mobile station,and outputs the determined RS phases to control information generatingsection 102. For example, in cases where the number of PUCCHs requiredis small and only two Walsh codes W #0=[1,1,1,1] and W#1=[1, −1, −1,1]are used, Walsh codes in the positions where RSs of CQI are transmittedare (+, +) and (−, −), and therefore uplink RS phase determining section101 determines to use (+, −), which is orthogonal to both (+, +) and (−,−) for an RS phase.

Control information generating section 102 generates control informationfor reporting a resource allocation result and the RS phases received asinput from RS phase determining section 101, for each mobile station,and outputs the control information to encoding section 103. The controlinformation for each mobile station includes mobile station IDinformation showing to which mobile station the control information isaddressed. For example, the control information includes CRC that ismasked by an ID number of a mobile station to which control informationis reported as mobile ID information. The control information for eachmobile station is encoded in encoding section 103, modulated inmodulating section 104 and received as input in mapping section 108.Further, according to the number of CCEs required to report controlinformation, control information generating section 102 allocates one ofa plurality of L1/L2CCHs to each mobile station and outputs a CCE numberassociated with the allocated L1/L2CCH, to mapping section 108. Forexample, in case where the number of CCEs required to report controlinformation to mobile station #1 is one and therefore L1/L2CCH #1 isallocated to mobile station #1, control information generating section102 outputs CCE number #1 to mapping section 108. Further, in case wherethe number of CCEs required to report control information to mobilestation #1 is four and therefore L1/L2CCH #6 is allocated to mobilestation #1, control information generating section 102 outputs CCEnumbers #8 to #11 to mapping section 108.

Encoding section 105 encodes transmission data (i.e., downlink data) foreach mobile station, and outputs the transmission data to retransmissioncontrolling section 106.

Upon first transmission, retransmission controlling section 106 holdsencoded transmission data per mobile station, and outputs transmissiondata to modulating section 107. Retransmission controlling section 106holds transmission data until an ACK from each mobile station isreceived as input from deciding section 118. Further, when a NACK fromeach mobile station is received as input from deciding section 118, thatis, when retransmission is performed, retransmission controlling section106 outputs the transmission data matching this NACK, to modulatingsection 107.

Modulating section 107 modulates the encoded transmission data receivedas input from retransmission controlling section 106, and outputs thetransmission data to mapping section 108.

When control information is transmitted, mapping section 108 mapscontrol information received as input from modulating section 104, onphysical resources according to the CCE number received as input fromcontrol information generating section 102, and outputs the controlinformation to IFFT section 109. That is, mapping section 108 mapscontrol information for each mobile station, on a subcarrier associatedwith a CCE number in a plurality of subcarriers forming an OFDM symbol.

By contrast with this, when downlink data is transmitted, mappingsection 108 maps the transmission data for each mobile station, on thephysical resources according to the resource allocation result, andoutputs the transmission data to IFFT section 109. That is, mappingsection 108 maps transmission data for each mobile station, on one of aplurality of subcarriers forming an OFDM symbol according to theresource allocation result.

IFFT section 109 generates an OFDM symbol by performing an IFFT of aplurality of subcarriers on which control information or transmissiondata is mapped, and outputs the OFDM symbol to CP (Cyclic Prefix) addingsection 110.

CP adding section 110 adds the same signal as the rear portion of theOFDM symbol as a CP to the head of that OFDM symbol.

Radio transmitting section 111 performs transmission processing such asD/A conversion, amplification and up-conversion with respect to the OFDMsymbol to which a CP is added, and transmits the OFDM symbol fromantenna 112 to mobile station 200 (FIG. 7).

Meanwhile, radio receiving section 113 receives the signal transmittedfrom mobile station 200 through antenna 112, and performs receivingprocessing such as down-conversion and A/D conversion with respect tothe received signal. Note that, in a received signal, an ACK/NACK signaltransmitted from a given mobile station and CQI signals transmitted fromother mobile stations are code-multiplexed.

CP removing section 114 removes the CP added to the signal afterreceiving processing.

Correlation processing section 115 finds a correlation value between thesignal received as input from CP removing section 114 and the ZCsequence used for first spreading in mobile station 200. That is, acorrelation value determined using the ZC sequence associated with thecyclic shift amount allocated to an ACK/NACK signal and a correlationvalue determined using ZC sequence associated with the cyclic shiftamount allocated to a CQI signal are outputted to separating section116.

Separating section 116 outputs the ACK/NACK signal to despreadingsection 117 and the CQI signal to RS combining section 119 based on thecorrelation values received as input from correlation processing section115.

Despreading section 117 despreads the ACK/NACK signal received as inputfrom despreading section 116 using a Walsh sequence used for secondspreading in mobile station 200, and outputs the despread signal todeciding section 118.

Deciding section 118 detects the ACK/NACK signal of each mobile stationby detecting a correlation peak of each mobile station using thedetection window set for each mobile station in the time domain. Forexample, in case where a correlation peak is detected in detectionwindow #1 for mobile station #1, deciding section 118 detects theACK/NACK signal from mobile station #1. Then, deciding section 118decides whether the detected ACK/NACK signal is an ACK or NACK, andoutputs an ACK or NACK from each mobile station, to retransmissioncontrolling section 106.

RS combining section 119 coordinates and combines the phases of aplurality of RSs of CQI received as input from separating section 116,and estimates a channel using the combined RS. The estimated channelinformation and the CQI signals received as input from separatingsection 116 are outputted to demodulating section 120.

Demodulating section 120 demodulates the CQI signal received as inputfrom RS combining section 119 using channel information, and decodingsection 121 decodes the demodulated CQI signal and outputs the CQIsignal.

By contrast with this, in mobile station 200 shown in FIG. 7, radioreceiving section 202 receives through antenna 201 an OFDM symboltransmitted from base station 100, and performs receiving processingsuch as down-conversion and A/D conversion with respect to the OFDMsymbol.

CP removing section 203 removes the CP added to the OFDM symbol afterreceiving processing.

FFT (Fast Fourier Transform) section 204 performs an FFT with respect tothe OFDM symbol to acquire the control information or downlink datamapped on a plurality of subcarriers, and outputs the result toextracting section 205.

To receive control information, extracting section 205 extracts thecontrol information from a plurality of subcarriers, and outputs thecontrol information to demodulating section 206. This controlinformation is demodulated in demodulating section 206, decoded indecoding section 207 and received as input in deciding section 208.

By contrast with this, to receive downlink data, extracting section 205extracts the downlink data addressed to mobile station 200 from aplurality of subcarriers according to the resource allocation resultreceived as input from deciding section 208, and outputs the downlinkdata to demodulating section 210. This downlink data is demodulated indemodulating section 210, decoded in decoding section 211 and receivedas input in CRC section 212.

CRC section 212 performs error detection with respect to the decodeddownlink data using a CRC check, and generates an ACK if CRC=OK (i.e.,no error) or generates a NACK if CRC=NG (i.e., error present) andoutputs the generated ACK/NACK signal to modulating section 213.Further, if CRC=OK (i.e., no error), CRC section 212 outputs the decodeddownlink data as received data.

Deciding section 208 performs blind decision as to whether or not thecontrol information received as input from decoding section 207 isaddressed to mobile station 200. For example, by performing demaskingusing the ID number of mobile station 200, deciding section 208 decidesthat the control information showing that CRC=OK (i.e., no error) isaddressed to mobile station 200. Then, deciding section 208 outputs thecontrol information addressed to mobile station 200, that is, thedownlink data resource allocation result for mobile station 200, toextracting section 205. Further, deciding section 208 decides a PUCCHnumber used to transmit an ACK/NACK signal from mobile station 200,based on the CCE number associated with a subcarrier on which thecontrol information addressed to mobile station 200 is mapped, andoutputs the decision result (i.e., PUCCH number) to controlling section209. For example, control information is mapped on the subcarrierassociated with CCE#1, and therefore deciding section 208 of mobilestation 200, to which above L1/L2CCH #1 is allocated, decides that PUCCH#1 associated with CCE#1 is the PUCCH for mobile station 200. Further,control information is mapped on subcarriers associated with CCE#8 toCCE#11, and therefore deciding section 208 of mobile station 200, towhich above L1/L2CCH #6 is allocated, decides that PUCCH #8 associatedwith CCE#8 of the smallest number among CCE#8 to CCE#11, is the PUCCHfor mobile station 200. Furthermore, deciding section 208 extracts theRS phases included in the control information received as input fromdecoding section 207, and outputs the RS phases to controlling section209.

According to the PUCCH number received as input from deciding section208, controlling section 209 controls a cyclic shift amount of a ZCsequence used for first spreading in spreading section 214 and spreadingsection 219, and a Walsh sequence used for second spreading in spreadingsection 217. That is, controlling section 209 sets the ZC sequence of acyclic shift amount associated with the PUCCH number received as inputfrom deciding section 208 in spreading section 214 and spreading section219, and sets a Walsh sequence associated with the PUCCH number receivedas input from deciding section 208, in spreading section 217. Further,controlling section 209 controls RS phase adding section 222 accordingto the RS phases received as input from deciding section 208. Further,controlling section 209 controls transmission signal selecting section223 to select transmission of a CQI signal if base station 100 commandstransmission of CQI in advance, and to transmit the ACK/NACK signalgenerated based on CRC=NG (i.e., error present) in deciding section 208if base station 100 does not command transmission of CQI in advance.

Modulating section 213 modulates the ACK/NACK signal received as inputfrom CRC section 212, and outputs the ACK/NACK signal to spreadingsection 214. Spreading section 214 performs first spreading of theACK/NACK signal using the ZC sequence set in controlling section 209,and outputs the ACK/NACK signal after first spreading, to IFFT section215. IFFT section 215 performs an IFFT with respect to the ACK/NACKsignal after first spreading, and outputs the ACK/NACK signal after theIFFT, to CP adding section 216. CP adding section 216 adds the samesignal as the rear portion of the ACK/NACK signal after the IFFT, to thehead of the ACK/NACK signal as a CP. Spreading section 217 performssecond spreading of the ACK/NACK signal to which the CP is added, usinga Walsh sequence set in controlling section 209, and outputs theACK/NACK signal after second spreading, to transmission signal selectingsection 223. Further, modulating section 213, spreading section 214,IFFT section 215, CP adding section 216 and spreading section 217function as an ACK/NACK signal transmission processing means.

Modulating section 218 modulates a CQI signal and outputs the CQI signalto spreading section 219. Spreading section 219 spreads the CQI signalusing the ZC sequence set in controlling section 209, and outputs thespread CQI signal to IFFT section 220. IFFT section 220 performs an IFFTwith respect to the spread CQI signal, and outputs the CQI signal afterthe IFFT, to CP adding section 221. CP adding section 221 adds the samesignal as the rear portion of the CQI signal after the IFFT, to the headof that CQI signal as a CP.

RS phase adding section 222 adds the phases set in controlling section209, to the CQI signal received as input from CP adding section 221, andoutputs the CQI signal to which the phases are added, to transmissionsignal selecting section 223.

According to the setting in controlling section 209, transmission signalselecting section 223 selects one of the ACK/NACK signal received asinput from spreading section 217 and the CQI signal received as inputfrom RS phase adding section 222, and outputs the selected signal toradio transmitting section 224 as a transmission signal.

Radio transmitting section 224 performs transmission processing such asD/A conversion, amplification and up-conversion with respect to thetransmission signal received as input from transmission signal selectingsection 223, and transmits the transmission signal from antenna 201 tobase station 100 (FIG. 6).

Next, how a CQI signal is generated in mobile station 200 shown in FIG.7 will be explained. Note that, instead of transmitting an ACK/NACKsignal and CQI signal at the same time, mobile station 200 transmits oneof these. Further, the ACK/NACK signal is generated as shown in FIG. 7.

As shown in FIG. 5, five symbols of information are spread by spreadingsection 219 using the ZC sequence, the CP is added by CP adding section221 and then CQI is mapped over the five SC-FDMA symbols. Further, theZC sequence is mapped on two SC-FDMA symbols of the second symbol andthe sixth symbol as RSs.

Here, assume that base station 100 uses only two Walsh sequencesdetermined in advance for ACK/NACK transmission. That is, although thesystem can utilize four Walsh sequences, base station 100 designates useof only two

Walsh sequences W #0=[1, 1, 1, 1] and W#1=[1, −1, −1,1]. Mobile station200 transmitting ACK/NACK signals use only these Walsh sequences.Similarly, base station 100 designates use of (+, −) as the RS phases(the phase of the second symbol and the phase of the sixth symbol) ofCQI. That is, as described above, RS phase adding section 222 of mobilestation 200 in FIG. 7 transmitting CQI signals adds RS phases of CQI. Atthis time, how an ACK/NACK signal is transmitted and a CQI signal isgenerated is as shown in FIG. 8.

As shown in FIG. 8, Walsh sequence W #1 is applied to the data(corresponding to the outlined portion in the figure) of an ACK/NACKsignal. By contrast with this, “+” is added to an RS of CQI as the RSphase of the second symbol, and “−” is added to an RS of CQI as the RSphase of the sixth symbol. That is, subsequences (W₁ and W₂) of theWalsh sequence multiplexed with RSs of CQI and applied to the secondsymbol and sixth symbol of the ACK/NACK signal show (+, +) or (−, −),and, RS combining section 119 of base station 100 coordinates andcombines the phases of RSs of CQI (by inverting the reception result inthe sixth symbol), thereby inverting in the second symbol and sixthsymbol the phases of the signal spread using Walsh sequences, so thatthe phases cancel each other and interference from an ACK/NACK signal toRSs of CQI can be reduced.

Further, the Walsh sequence and the selection result of RS phases of CQIin given base station 100 are broadcast from base station 100 at regularintervals.

In this way, according to Embodiment 1, by making RSs of CQI transmittedfrom a mobile station orthogonal to second spreading codes of anACK/NACK signal multiplexed in the same positions as these RSs andcoordinating and averaging RS phases of CQI in the base station, theinfluence of noise can be reduced and interference received fromACK/NACK signals transmitted from other mobile stations can be reduced,so that it is possible to improve the accuracy of channel estimation inCQI and improve the accuracy of receiving CQI signals. Further, anACK/NACK signal is despread when the ACK/NACK signals are received andtherefore reverse phases of RS portions of CQI are added, so that it ispossible to reduce interference signals from RS portions of CQI to anACK/NACK signal. That is, it is possible to improve the accuracy ofreceiving ACK/NACK signals.

Further, although a case has been explained with the present embodimentwhere two of four Walsh sequences that can be utilized in the system areused, it is equally possible to determine the priority for four Walshsequences in advance and use Walsh sequences in order from the highestpriority. A case will be explained below where priority is assigned tofour Walsh sequences.

The base station broadcasts to all mobile stations that each mobilestation must transmit CQI using the phases orthogonal to subsequences(W₁ and W₂) of the Walsh sequence that is frequently used. The amount ofinterference to RSs of CQI increases depending on the number of mobilestations using Walsh sequences that are not orthogonal to RSs of CQI,and, by making the RS phases of CQI and Walsh sequences that arefrequently used orthogonal to each other, it is possible to reduce thetotal amount of interference to RSs of CQI. This situation is shown inFIG. 9.

Further, even if the base station does not broadcast information relatedto RS phases of uplink CQI in advance, mobile stations may designate RSphases of CQI every time according to the timings to transmit CQI.Although which mobile station transmits an uplink signal in a givensubframe or which uplink code resources are used to perform transmissionin mobile stations changes on a per subframe basis, the base station haslearned in advance which Walsh sequence is more frequently used in aframe for transmitting CQI, and, consequently, can adaptively commandmobile stations to transmit RSs of CQI by making the RSs of CQI and theWalsh sequence (W₁ and W₂) that is more frequently used orthogonal toeach other. By this means, it is possible to reduce the total amount ofinterference to RSs of CQI. This situation is shown in FIG. 10. Further,a case where the positions of RSs of CQI are multiplexed with RSs of anACK/NACK is shown in FIG. 11.

Further, in case where a second spreading sequence other than a Walshsequence is used for an ACK/NACK, whether the codes of S1 and S2 are thein-phases or the reverse phases is checked by focusing on the codes inportions (S1 and S2) associated with RSs of CQI in the second spreadsequence (S0, S1, S2 and S3) used in this base station.

That is, whether the second and third codes in the second spreadsequence used in the base station are in-phase sequences or reversephase sequences checked, and, if a greater number of sequences in whichthe second and third symbols are in-phases are used, (+, −) may be usedas the RS phases and, if a greater number of sequences in which thesecond and third symbols are reverse phases are used, (+, +) may be usedas the RS phases.

Note that (−, +) and (−, −) may be used as RS phases instead of (+, −)and (+, +).

Embodiment 2

The configurations of a base station and mobile station according toEmbodiment 2 of the present invention are the same as the configurationsshown in FIG. 6 and FIG. 7 of Embodiment 1, and therefore will beexplained employing FIG. 6 and FIG. 7.

How an ACK/NACK signal and CQI signal are multiplexed (i.e., resourceallocation) according to Embodiment 2 of the present invention is shownin FIG. 12. Here, assume that the base station performs resourceallocation shown in FIG. 12. Note that the horizontal axis representsthe cyclic shift amount and the vertical axis represents the Walshsequence.

Further, it is focused that RSs of CQI are mainly interfered fromACK/NACK signals spread using ZC sequences associated with adjacentcyclic shift amounts. To be more specific, RSs of CQI receivesignificant interference from nearby ACK/NACK signals of a small cyclicshift amount, and apply great interference to nearby ACK/NACK signals ofa high cyclic shift amount.

As shown in FIG. 12, the mobile station that transmits CQI #1 spreadsand transmits a CQI signal using the ZC sequence associated with acyclic shift amount of 2. At this time, CQI #1 receives the greatestinterference from ACK #5 and, therefore, focusing on the phases (W₁=1and W₂=−1) of W₁ and W₂ of ACK #5, uplink RS phase determining section101 of base station 100 determines (+, +) as the RS phases of CQI.Further, CQI #2 receives interference from ACK #3 and ACK #11 and,therefore, focusing on the phases (W₁=1 and W₂=−1) of W₁ and W₂ of ACK#3 and the phases (W₁=−1 and W₂=−1) of W₁ and W₂ of ACK #11, uplink RSphase determining section 101 of base station 100 determines (+, −) asthe RS phases of CQI.

In this way, according to Embodiment 2, the RS phases of CQI aredetermined focusing on Walsh codes of an ACK/NACK signal that actuallyreceives significant interference, so that it is possible to effectivelyreduce the amount of interference in RSs.

Further, although the resource allocation shown in FIG. 12 is assumedwith the present embodiment, the base station may allocate ACK/NACKresources freely. For example, in case where an ACK/NACK signal and CQIsignal are multiplexed as shown in FIG. 13, three ACK #2, ACK #8 and ACK#9 are adjacent to CQI #1 and more W #2=[1, 1, −1, −1] are used.Therefore, uplink RS phase determining section 101 of base station 100determines (+, +) as the RS phases of CQI #1. Further, three ACK #4, ACK#11 and ACK #16 are adjacent to CQI #2 and the number of mobile stationsusing W #0=[1, 1, 1, 1] and W #1=[1, −1, −1,1] is greater than thenumber of mobile stations using W #2. Therefore, uplink RS phasedetermining section 101 of base station 100 determines (+, −) as the RSphases of CQI #2.

Further, focusing on that the required error rate of CQI is around 10⁻²while the required error rate of an ACK/NACK signal is around 10⁻⁴, theRS phases of CQI may be set such that ACK/NACK quality furtherincreases. That is, as described above, by making the RS phases of CQIand W₁ and W₂ of an ACK/NACK signal orthogonal to each other, it ispossible to reduce interference to

CQI as well as interference from CQI to the ACK/NACK signal. Therefore,in the case shown in FIG. 13, the RS phases are set to reduce theinfluence upon ACK #9, which is interfered from CQI #1 and ACK #11,which are interfered from CQI #2. That is, ACK #9 and ACK #11 both use W#2 and therefore the RS phases set both in CQI #1 and CQI #2 are (+, +),respectively.

Embodiment 3

A case will be explained with Embodiment 3 of the present inventionwhere a CQI signal and a response signal (i.e., ACK/NACK signal) aretransmitted at the same time. That is, although the base stationspecifies with respect to a mobile station the timing to transmit a CQIsignal, cases occur depending on the timing to allocate the downlinkdata signal of the base station where a given mobile station transmits aCQI signal and a response signal (i.e., an ACK or NACK) in response to adownlink data signal at the same time. At this time, the CQI signal andresponse signal that are transmitted at the same time are collectivelyrepresented as “CQI+response signal.” Note that the CQI+response signalis represented as “CQI+NACK signal” in case where the response signal isa NACK and is represented as “CQI+ACK signal” in case where the responsesignal is an ACK.

FIG. 14 shows a configuration of base station 150 according toEmbodiment 3 of the present invention. Note that FIG. 14 differs fromFIG. 6 in changing uplink RS phase determining section 101 to RS phasedetermining section 151 and changing RS combining section 119 to RScombining section 152.

Uplink RS phase determining section 151 determines whether the RS phases(i.e., the phase of the second symbol and the phase of the sixth symbol)of a CQI+response signal transmitted from a mobile station defines that(+, −) is CQI+ACK and (+, +) is CQI+NACK, or defines that (+, +) isCQI+ACK and (+, −) is CQI+NACK, and outputs the determined definition ofthe RS phases to control information generating section 102 and RScombining section 152.

For example, in case where the number of required PUCCHs is small andonly two W #0=[1, 1, 1, 1] and W #1=[1, −1, −1,1] are used as Walshcodes, Walsh codes in the positions where RSs of CQI are transmitted are(+, +) and (−, −), and therefore uplink RS phase determining section 151allocates (+, −) that is orthogonal to both Walsh codes as RS phases andthen determines to define that (+, +) is CQI+ACK and define that (+, −)is CQI+NACK.

In case where a mobile station transmits only a CQI signal RS combiningsection 152 coordinates and combines the phases of a plurality of RSs ofCQI received as input from separating section 116, and estimates achannel using the combined RS. The estimated channel information and theCQI signal received as input from separating section 116 are outputtedto demodulating section 120.

Further, in case where a mobile station transmits a CQI+response signal,RS combining section 152 decides whether power of a plurality of RSs ofCQI received as input from separating section 116 is greater either incase where the RS phases are coordinated assuming (+, +) or in casewhere the RS phases are coordinated assuming (+, −), and decides thatthe phases of greater power are the RS phases of CQI. Using thisdecision result of the RS phases and the definition of the RS phasesreceived as input from uplink RS phase determining section 151, whetherthe response signal transmitted at the same time with CQI is an ACK orNACK is decided. That is, RS combining section 152 provide twocorrelators having coefficients of (+, +) and coefficients of (+, −) ofRS signals, and decides whether the signal transmitted at the same timewith CQI is an ACK or NACK using the outputs from these correlators.This decision result is outputted to retransmission controlling section106. Further, based on this decision result, the RSs obtained bycoordinating and combining these phases are used to estimate a channelfor decoding the data part of CQI. The estimated channel information andthe CQI signal received as input from separating section 116 areoutputted to demodulating section 120.

Next, FIG. 15 shows the configuration of mobile station 250 according toEmbodiment 3 of the present invention. Note that FIG. 15 differs fromFIG. 7 in changing controlling section 209 to controlling section 251.

According to the PUCCH number received as input from deciding section208, controlling section 251 controls the cyclic shift amount of the ZCsequence used for first spreading in spreading section 214 and spreadingsection 219, and the Walsh sequence used for second spreading inspreading section 217. That is, controlling section 251 sets the ZCsequence of the cyclic shift amount associated with the PUCCH numberreceived as input from deciding section 208, in spreading section 214and spreading section 219, and sets the Walsh sequence associated withthe PUCCH number received as input from deciding section 208, inspreading section 217. Further, controlling section 251 controls RSphase adding section 222 according to the RS phases received as inputfrom deciding section 208.

Further, controlling section 251 controls transmission signal selectingsection 223 to select transmission of a CQI signal, that is,transmission of an output from RS phase adding section 222, if basestation 150 commands transmission of CQI in advance, and to selecttransmission of an ACK/NACK signal generated based on CRC=NG (i.e.,error present) in deciding section 208, that is, transmission of anoutput from spreading section 217, if base station 150 does not commandtransmission of a CQI signal.

Furthermore, in case where base station 150 commands transmission of CQIin advance and the ACK/NACK signal needs to be transmitted with CQI atthe same time, controlling section 251 determines the RS phases for RSphase adding section 222, according to the RS phases designated by basestation 150 and the signal from CRC section 212. For example, in casewhere base station 150 designates in advance that (+, +) is CQI+ACK and(+, −) is CQI+NACK as the definition of the RS phases, and CQI and aNACK signal are transmitted at the same time, base station 150 commandsRS phase adding section 222 to use the (+, −) phases.

Next, how mobile station 250 shown in FIG. 15 generates a CQI+responsesignal, will be explained. That is, a case will be explained wheremobile station 250 transmits an ACK/NACK signal and a CQI signal at thesame time.

As shown in FIG. 15 and FIG. 16, five symbols of information in a CQIsignal are spread using the ZC sequence in spreading section 219, addedCPs by CP adding section 221 and mapped over five SC-FDMA symbols.Further, ZC sequences are mapped over two SC-FDMA symbols of the secondsymbol and sixth symbol as RSs.

Here, assume that base station 150 uses only two Walsh sequencesdetermined in advance for ACK/NACK signal transmission. That is,although the system can utilize four Walsh sequences, base station 150designates use of only two Walsh sequences W #0=[1, 1, 1, 1] and W#1=[1,−1, −1,1]. Mobile station 250 transmitting only ACK/NACK signals usesonly these Walsh sequences. Similarly, base station 150 broadcasts that,for the RS phases of CQI (i.e., the phase of the second symbol=X₁ andthe phase of the sixth symbol=X₂), (+, +) is defined as CQI+ACK and (+,−) is defined as CQI+NACK. That is, as described above, RS phase addingsection 222 of mobile station 250 in FIG. 15 that transmits aCQI+response signal adds the RS phases of CQI. At this time, how anACK/NACK signal and CQI signal are generated is as shown in FIG. 16.

As shown in FIG. 8, Walsh sequence W #1 is applied to data(corresponding to the outlined portion in the figure) of an ACK/NACKsignal. By contrast with this, “+” is added to RSs of a CQI+NACK signalas the RS phase of the second symbol, and “−” is added to RSs of aCQI+NACK signal as the RS phase of the sixth symbol. That is,subsequences (W₁ and W₂) of the Walsh sequence applied to the secondsymbol and sixth symbol of the ACK/NACK signal multiplexed with the RSsof CQI show (+, +) or (−, −), the ACK/NACK signal does not produceinterference to the result that is outputted by coordinating the phases(by inverting the reception result in the sixth symbol) assuming thatthe coefficients are (+, −) when RS combining section 152 of basestation 150 decides the RSs of CQI. This is because correlationprocessing used to receive a CQI+NACK signal inverts the phases of thesecond symbol and sixth symbol of a signal spread using the Walshsequence and the phases cancel each other, so that it is possible toreduce interference from the ACK/NACK signal to RSs of the CQI+NACKsignal. That is, it is possible to reduce interference from surroundingindividual ACK/NACK signals to CQI+NACK signals.

Note that the Walsh sequence and definition of RS phases of CQI in givenbase station 150 are broadcast from base station 150 at regularintervals.

In this way, according to Embodiment 3, by making RSs of a CQI+NACKsignal transmitted from a mobile station orthogonal to second spreadingcodes of an ACK/NACK signal multiplexed in the same positions as theseRSs and by, in base station 150, coordinating and averaging the RSphases of the CQI+NACK signal, the influence of noise can be reduced andinterference from ACK/NACK signals transmitted from other mobilestations can be reduced, so that it is possible to improve the accuracyof deciding NACK signals when CQI+NACK signals are received.

In case where the base station fails to receive an ACK signal, the basestation transmits a downlink signal again even though data has reached aterminal. However, in this case, only a little downlink resources arewasted, which does not influence the system significantly. However, incase where the base station fails to receive a NACK signal, the basestation learns that the mobile station has successfully received dataand does not retransmit data. Accordingly, in this case, required datadoes not reach the mobile station. In case where a mechanism isintroduced to check the content of data in an upper layer and requestdata that has not reached the terminal, from the base station again,although the problem that data does not arrive does not occur,significant delay in data transmission occurs in case where the basestation fails to receive a NACK signal. Therefore, according to thepresent embodiment, the efficiency of the system improves by improvingthe accuracy of deciding NACK signals when CQI+NACK signals arereceived.

Further, although a case has been explained with the present embodimentwhere two of four available Walsh sequences in the system are used, itis equally possible to determine the priority for four Walsh sequencesin advance and sequentially use Walsh sequences from the highestpriority. A case will be explained below where priority is assigned tofour Walsh sequences.

Base station 150 broadcasts to all mobile stations 250 that each mobilestation 250 must define the phases orthogonal to subsequences (W₁ andW₂) of the Walsh sequence that is frequently used, as CQI+NACK. Theamount of interference to RSs of CQI+NACK increases depending on thenumber of mobile stations that use Walsh sequences that are notorthogonal to RSs of a CQI+NACK signal, it is possible to reduce thetotal amount of interference to the RSs of the CQI+NACK signal by makingWalsh sequences that are frequently used and the RS phases of theCQI+NACK signals orthogonal to each other.

Further, even if base station 150 does not broadcast information relatedto the RS phases of the uplink CQI+NACK signal in advance, mobilestation 250 may designate the definition of the RS phases ofCQI+response signals every time depending on the timings to transmitCQI+response signals. Although which mobile station transmits an uplinksignal in a given subframe or which uplink code resources are used toperform transmission in a mobile station changes on a per subframebasis, base station 150 has learned in advance which Walsh sequence isfrequently used in a frame for transmitting a CQI+response signal, and,consequently can command mobile stations to transmit RSs of CQI +NACKsignals by making the RSs of the CQI+NACK signals and the Walsh sequence(W₁ and W₂) that is frequently used orthogonal to each other. By thismeans, it is possible to reduce the total amount of interference to theRSs of CQI+NACK signals.

Embodiment 4

The configurations of the base station and mobile station according toEmbodiment 4 of the present invention are the same as the configurationsshown in FIG. 14 and FIG. 15 according to Embodiment 3, and thereforewill be explained employing FIG. 14 and FIG. 15.

How an ACK/NACK signal and CQI+response signal are multiplexed (i.e.,resource allocation) according to Embodiment 4 of the present inventionis shown in FIG. 17. Here, assume that base station 150 has performedresource allocation shown in FIG. 17 Note that the horizontal axisrepresents the cyclic shift amount and the vertical axis represents theWalsh sequence.

Further, note that the RSs of a CQI+response signal are mainlyinterfered from ACK/NACK signals spread using ZC sequences associatedwith consecutive cyclic shift amounts. To be more specific, RSs of aCQI+response signal receive significant interference from a nearbyACK/NACK signal of a small cyclic shift amount, and apply significantinterference to a nearby ACK/NACK signal of a high cyclic shift amount.

As shown in FIG. 17, mobile station 250 that transmits CQI+NACK #1spreads and transmits CQI+NACK #1 using the ZC sequence associated withcyclic shift amount of 2. At this time, CQI+NACK #1 receives thegreatest interference from ACK #5 and, therefore, uplink RS phasedetermining section 151 of base station 150 determines (+, +) as the RSphases of CQI+NACK #1 focusing on the phases (W₁=1 and W₂=−1) of W₁ andW₂ of ACK #5.

Next, interference from CQI+response signals to neighboring ACK/NACKsignals is taken into account. When a given mobile station transmits CQIand a response signal at the same time, response signals are ACK signalsat the rate of 90 percent. This is because base station 150 performsadaptive modulation processing such that the transmission target errorrate of downlink data becomes around 10 percent. That is, reducinginterference from a CQI+ACK signal to neighboring ACK/NACK signals iseffective to reduce interference from a CQI+response signal toneighboring ACK/NACK signals. Here, back to FIG. 17, CQI+ACK #2 isfocused. CQI+ACK #2 applies significant interference to ACK #7. Focusingon the phases (W₁=−1 and W₂=1) of W₁ and W₂ of ACK #7, uplink RS phasedetermining section 151 of base station 150 determines (+, +) as the RSphases of CQI+ACK #2.

By this means, base station 150 performs despreading when ACK #7 isreceived and therefore reverse phases of RS portions of a CQI+ACK signalare added, so that it is possible to reduce interference signals fromthe RS portions of the CQI+AKC signal to ACK #7.

In this way, according to Embodiment 4, the RS phases of a CQI+responsesignal are determined focusing on Walsh codes of an ACK/NACK signal thatactually receives and applies significant interference, so that it ispossible to reduce the amount of interference that RSs of a CQI+responsesignal receives and the amount of interference that RSs of theCQI+response signal applies.

Embodiments have been explained above.

Further, although the above embodiments have been explained assumingthat one base station forms one cell and the base station performs thesame RS code control and ACK/NACK resource control in its managing area,the present invention is also applicable to a case where, for example,one base station forms a plurality of cells by means of directionalantennas, manages a plurality of cells and controls these cellsindependently.

Also, although cases have been described with the above embodiments asexamples where the present invention is configured by hardware, thepresent invention can also be realized by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSIs, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor whereconnections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosures of Japanese Patent Application No. 2007-211101, filed onAug. 13, 2007 and Japanese Patent Application No. 2007-280797, filed onOct. 29, 2007, including the specifications, drawings and abstracts, areincorporated herein by reference in their entirety.

INDUSTRIAL APPLICABILITY

The radio transmitting apparatus and radio transmitting method accordingto the present invention can improve CQI receiving performance, and areapplicable to, for example, a wireless communication base stationapparatus and wireless communication mobile station apparatus in, forexample, a mobile communication system.

1. A radio transmitting apparatus comprising: response signaltransmission processing circuitry which, in operation, spreads aresponse signal using an orthogonal sequence; reference signal phaseadding circuitry which, in operation, adds a phase to a reference signalof channel quality information multiplexed with the response signalspread using the orthogonal sequence; and a transmitter which, inoperation, transmits a channel quality information signal including thereference signal to which the phase is added.
 2. The radio transmittingapparatus according to claim 1, wherein the reference signal phaseadding circuitry adds to the reference signal the phase according topart of the orthogonal sequence of higher priority in the orthogonalsequence to which priority of use is assigned.
 3. The radio transmittingapparatus according to claim 1, wherein the reference signal phaseadding circuitry adds the phase to the reference signal according to anumber of radio transmitting apparatuses that use a pair of orthogonalsequences in which part of codes for spreading the response signalmultiplexed with the reference signal is an in-phase, and a number ofradio transmitting apparatuses that use a pair of orthogonal sequencesin which part of codes for spreading the response signal multiplexedwith the reference signal is a reverse phase.
 4. The radio transmittingapparatus according to claim 1, wherein the reference signal phaseadding circuitry adds to the reference signal the phase according topart of codes used to perform second spreading of a response signalwhich is multiplexed with the reference signal and which is subjected tofirst spreading using a Zadoff-Chu sequence which is adjacent to aZadoff-Chu sequence used to spread channel quality information and whichis associated with a smaller cyclic shift amount than a cyclic shiftamount of the Zadoff-Chu sequence used to spread the channel qualityindicator.
 5. The radio transmitting apparatus according to claim 1,wherein: orthogonal sequences are used to perform second spreading ofthe response signal that is subjected to first spreading using aZadoff-Chu sequence associated with a cyclic shift amount which isconsecutive to a cyclic shift amount of the Zadoff-Chu sequence used tospread the channel quality information; and the reference signal phaseadding circuitry adds the phase to the reference signal according to anumber of radio transmitting apparatuses using the orthogonal sequencein which part of codes used to perform second spreading of the responsesignal multiplexed with the reference signal is an in-phase and a numberof radio transmitting apparatuses that use the orthogonal sequence inwhich part of codes used to perform second spreading of the responsesignal multiplexed with the reference signal is a reverse phase.
 6. Theradio transmitting apparatus according to claim 1, wherein, in casewhere a signal superimposing the response signal on the channel qualityindicator has a phase orthogonal to part of an orthogonal sequence usedby an acknowledgement signal that applies the greatest interference tothe signal, the reference signal phase adding circuitry makes theresponse signal to be superimposed on the channel quality information anegative acknowledgement signal.
 7. The radio transmitting apparatusaccording to claim 6, wherein the reference signal phase addingcircuitry adds to the reference signal of the superimposed signal aphase according to part of the orthogonal sequence of higher priority inthe orthogonal sequence to which priority of use is assigned.
 8. Theradio transmitting apparatus according to claim 1, wherein, in casewhere a signal superimposing the response signal on the channel qualityinformation has a phase orthogonal to part of an orthogonal sequenceused by an acknowledgement signal that applies the greatest interferenceto the signal, the reference signal phase adding circuitry makes theresponse signal to be superimposed on the channel quality information anacknowledgement signal.
 9. A radio transmitting method comprising:spreading a response signal using an orthogonal sequence; adding a phaseto a reference signal of channel quality information multiplexed withthe response signal spread using the orthogonal sequence; andtransmitting a channel quality information signal including thereference signal to which the phase is added.
 10. The radio transmittingmethod according to claim 9, wherein the adding includes adding to thereference signal the phase according to part of the orthogonal sequenceof higher priority in the orthogonal sequence to which priority of useis assigned.
 11. The radio transmitting method according to claim 9,wherein the adding includes adding the phase to the reference signalaccording to a number of radio transmitting apparatuses that use a pairof orthogonal sequences in which part of codes for spreading theresponse signal multiplexed with the reference signal is an in-phase,and a number of radio transmitting apparatuses that use a pair oforthogonal sequences in which part of codes for spreading the responsesignal multiplexed with the reference signal is a reverse phase.
 12. Theradio transmitting method according to claim 9, wherein the addingincludes adding to the reference signal the phase according to part ofcodes used to perform second spreading of a response signal which ismultiplexed with the reference signal and which is subjected to firstspreading using a Zadoff-Chu sequence which is adjacent to a Zadoff-Chusequence used to spread channel quality information and which isassociated with a smaller cyclic shift amount than a cyclic shift amountof the Zadoff-Chu sequence used to spread the channel quality indicator.13. The radio transmitting method according to claim 9, wherein:orthogonal sequences are used to perform second spreading of theresponse signal that is subjected to first spreading using a Zadoff-Chusequence associated with a cyclic shift amount which is consecutive to acyclic shift amount of the Zadoff-Chu sequence used to spread thechannel quality information; and the adding includes adding the phase tothe reference signal according to a number of radio transmittingapparatuses using the orthogonal sequence in which part of codes used toperform second spreading of the response signal multiplexed with thereference signal is an in-phase and a number of radio transmittingapparatuses that use the orthogonal sequence in which part of codes usedto perform second spreading of the response signal multiplexed with thereference signal is a reverse phase.
 14. The radio transmitting methodaccording to claim 9, wherein, in case where a signal superimposing theresponse signal on the channel quality indicator has a phase orthogonalto part of an orthogonal sequence used by an acknowledgement signal thatapplies the greatest interference to the signal, the adding includesadding the response signal to be superimposed on the channel qualityinformation a negative acknowledgement signal.
 15. The radiotransmitting method according to claim 14, wherein the adding includesadding to the reference signal of the superimposed signal a phaseaccording to part of the orthogonal sequence of higher priority in theorthogonal sequence to which priority of use is assigned.
 16. The radiotransmitting method according to claim 9, wherein, in case where asignal superimposing the response signal on the channel qualityinformation has a phase orthogonal to part of an orthogonal sequenceused by an acknowledgement signal that applies the greatest interferenceto the signal, the adding includes making the response signal to besuperimposed on the channel quality information an acknowledgementsignal.